Shocking, fascinating, entirely unsurprising: the leaked documents, if authentic, confirm what we suspected but could not prove. The Heartland Institute, which has helped lead the war against climate science in the United States, is funded among others by tobacco firms, fossil fuel companies and one of the billionaire Koch brothers.

It appears to have followed the script written by a consultant to the Republican party, Frank Luntz, in 2002. "Should the public come to believe that the scientific issues are settled, their views about global warming will change accordingly. Therefore, you need to continue to make the lack of scientific certainty a primary issue in the debate."

Luntz's technique was pioneered by the tobacco companies and the creationists: teach the controversy. In other words, insist that the question of whether cigarettes cause lung cancer, natural selection drives evolution, or burning fossil fuels causes climate change, is still wide open, and that both sides of the "controversy" should be taught in schools and thrashed out in the media.

The leaked documents appear to show that, courtesy of its multimillionaire donors, the institute has commissioned a global warming curriculum for schools which teaches that "whether humans are changing the climate is a major scientific controversy" and "whether CO2 is a pollutant is controversial".

The institute has claimed it is "a genuinely independent source of research and commentary" and that "we do not take positions in order to appease or avoid losing support from individual donors". But the documents, if authentic, reveal that its attacks on climate science have been largely funded by a single anonymous donor and that "we are extinguishing primarily global warming projects in pace with declines in his giving".

The climate change deniers it funds have made similar claims to independence. For example, last year Fred Singer told a French website: "Of course I am not funded by the fossil fuel lobbies. It's a completely absurd invention." The documents suggest that the institute, funded among others by the coal company Murray Energy, the the oil company Marathon and the former Exxon lobbyist Randy Randol has been paying him $5,000 a month.

Robert Carter has claimed he "receives no research funding from special interest organisations". But the documents suggest that Heartland pays him $1,667 a month. Among the speakers at its conferences were two writers for the Telegraph (Christopher Booker and James Delingpole). The Telegraph group should now reveal whether and how much they were paid by the Heartland Institute.

It seems to be as clear an illustration as we have yet seen of the gulf between what such groups call themselves and what they really are. Invariably, organisations arguing for regulations to be removed, top taxes to be reduced and other such billionaire-friendly policies, call themselves free-market or conservative thinktanks. But according to David Frum, formerly a fellow at one such group – the American Enterprise Institute – they "increasingly function as public relations agencies". The message they send to their employees, he says, is "we don't pay you to think, we pay you to repeat".

The profits of polluting or reckless companies and banks and the vast personal fortunes of their beneficiaries are largely dependent on the regulations set by governments. This is why the "thinktanks" campaign for small government. If regulations robustly defend the public interest, the profits decline. If they are weak, the profits rise. Billionaires and big business buy influence to insulate themselves from democratic control. It seems to me that the so-called thinktanks are an important component of this public relations work.

Their funding, in most cases, is opaque. When I challenged some of the most prominent of such groups in the UK, only one would reveal its donors' identity. The others refused. Disgracefully, their lack of accountability does not prevent some of them from registering as charities and claiming tax exemption.

The Charity Commission in England and Wales – negligent, asleep at the wheel – is becoming a threat to democracy. These organisations are not trying to restore historic buildings or rescue distressed donkeys. They are seeking to effect political change in highly contentious areas. The minimum requirement for all such groups – whether they are on the left or on the right – is that they should disclose their major sources of income so that we know on whose behalf they speak. The commission is providing cover for multimillionaires and corporations who are funding undisclosed campaigns to enhance their own wealth under the guise of charity, and obliging the rest of us to pay for it through tax exemptions. If that's charity, a police siren is music.

The use of so-called thinktanks on both sides of the Atlantic seems to me to mirror the use of super-political action committees (superPACs) in the US. Since the supreme court removed the limits on how much one person could give to a political campaign, the billionaires have achieved almost total control over politics. An article last week on TomDispatch revealed that in 2011, just 196 donors provided nearly 80% of the money raised by superPACs.

The leading Republican candidates have all but abandoned the idea of mobilising popular support. Instead they use the huge funds they raise from billionaires to attack the credibility of their opponents through television ads. Yet more money is channelled through 501c4 groups – tax-exempt bodies supposedly promoting social welfare – which (unlike the superPACs) don't have to reveal the identity of their donors. TomDispatch notes that "serving as a secret slush fund for billionaires evidently now qualifies as social welfare."

The money wins. This is why Republicans swept up so many seats in the mid-term elections, and why the surviving Democrats were scarcely distinguishable from their rivals. It is why Obama, for all his promise, appears incapable of governing in the public interest. What can he tell the banks: "Do what I say or I won't take your money any more"? How can he tax the billionaires when they have their hands around his throat? Where your treasure is, there will your heart be also.

This is plutocracy, pure and simple. The battle for democracy is now a straight fight against the billionaires and corporations reshaping politics to suit their interests. The first task of all democrats must be to demand that any group, of any complexion, seeking to effect political change should reveal its funders.